China and the United States faced several major sources of tension in their relations in 2013, overshadowing their efforts to build what they called a "new model" of ties between two major powers.

The Woodrow Wilson Center, a Washington-based research institute, examined those tensions this month as part of a panel discussion reviewing key developments in the U.S.-China relationship over the past year.

One prominent development was the inauguration of Chinese President Xi Jinping in March.

Assessing China’s new leader

President Barack Obama hosted Mr. Xi at California’s Sunnylands resort for an informal summit in June. It was their first meeting as the leaders of their countries.

U.S. President Barack Obama (R) and Chinese President Xi Jinping walk the grounds at The Annenberg Retreat at Sunnylands in Rancho Mirage, California Jun. 8, 2013.

"This is the first time we have had a Chinese leader who appears to believe that the United States and China should interact on an equal footing. We saw that with Sunnylands," Fish said.

"That is really going to change the tenor of U.S.-China relations in everything from human rights to trade and international politics."

Another panelist, history professor Jeffrey Wasserstrom of the University of California, said U.S. officials also learned that President Xi has much in common with his predecessors.

"Whenever there are new Chinese leaders who talk about economic and social reform, the United States hopes those leaders also want political reform," said Wasserstrom.

"But we were disappointed with Hu Jintao, and now we have been disappointed with Xi Jinping. It turns out he is an authoritarian, nationalist, modernizer who wants to tinker with the Chinese economy and social structure, much like Deng Xiaoping. Xi is not China's [version of Soviet reformer] Mikhail Gorbachev," he continued.

Toughening of Chinese territorial claims

China’s growing assertiveness in territorial disputes with its neighbors was another significant source of tension with the United States, which has military alliances with many of those neighbors.

Beijing declared the establishment of a large Air Defense Identification Zone, or ADIZ, off its eastern coast in November. It said all foreign aircraft passing through the zone had to share information with Chinese authorities or face consequences. The zone covers the disputed Senkaku/Diaoyu islands, controlled by Japan but claimed by China, and a South Korean research facility built on a submerged rock.

Handout picture taken by Japan Coast Guard shows a Chinese state-owned plane flying in airspace over the disputed island, called the Senkakus in Japanese and Diaoyus in Chinese, in the East China Sea, December 13, 2012

The United States and its allies Japan and South Korea quickly rejected China’s move and sent military aircraft through the area without informing Beijing. The Chinese government took no apparent enforcement action, leading some U.S. observers to describe the zone as a Chinese "own goal."

Panel moderator Robert Daly, who heads the Wilson Center’s Kissinger Institute on China and the United States, said the zone was not as damaging for Beijing as some think.

"From Beijing’s point of view, they are putting down markers and saying they will not [retract] their vague claims that this is a Chinese zone," said Daly.

"They have done this in part to be consistent about the Diaoyus/Senkakus. They probably feel that this is a win for them, and we should not gloat about own goals. I would not be surprised to see more Chinese zones, with perhaps a better rollout, in the Yellow Sea and the South China Sea in 2014," said Daly.

Other sources of tension

Another aggravation to U.S.-China ties was cybercrime, with both nations complaining that their government and corporate institutions were victims of hacking attacks originating from the other side.

Edward Snowden, who worked as a contract employee at the National Security Agency, speaks to The Guardian newspaper in Hong Kong, June 9, 2013.

That dispute escalated when former U.S. National Security Agency contractor Edward Snowden sought shelter in the Chinese territory of Hong Kong as he leaked details of U.S. cyber spying programs that, he claimed, targeted Chinese institutions, among others. China allowed Snowden to fly to Russia in June rather than accept a U.S. demand for his extradition. Washington expressed deep disappointment.

More tension emerged as Beijing cracked down on Internet activists who called for the upholding of human rights as promised in the 1982 Chinese constitution.

U.S.-based group Human Rights Watch reported that Chinese authorities detained at least 50 activists of the New Citizens’ Movement during the year.

Wilson Center panelist David Wertime, founder of online China magazine Tea Leaf Nation, said the crackdown scared many bloggers into self-censoring their advocacy for constitutional rights.

"Chinese authorities are very keen to tie some of these liberal ideas to the West," Wertime said.

"They have created an environment where speaking about [a need for] asset disclosure [by officials], speaking about constitutional reform has become seen as something that is off limits and threateningly Western. They have been quite successful at doing that in the last six months."

The United States criticized the crackdown, accusing China of acting contrary to international obligations and even to its own laws and constitution.

U.S. media irritate Chinese leaders

U.S.-China relations also came under strain as U.S. news media published more articles exposing the wealth of Chinese leaders and how their families profited from political connections.

Chinese Premier Wen Jiabao, whose family's wealth came under scrutiny from the New York Times. The Times also revealed Wen's daugher's lucractive contract with JP Morgan.

Such stories upset Beijing, which responded by delaying the renewal of visas for American and other Western journalists.

Foreign Policy’s Fish said the visa delays amount to a Chinese crackdown on Western media.

"The journalists at The New York Times and Bloomberg bureaus may not have their visas renewed, and that would represent a de facto expulsion for roughly two dozen journalists," he said.

"It also would be China's biggest move against the foreign press arguably since [the Tiananmen Square crackdown in] 1989, the Cultural Revolution [of the 1960 and 70s], or even the founding of the People’s Republic of China in 1949. So it is a very tense time for foreign correspondents in Beijing," Fish continued.

U.S. Vice President Joe Biden complained directly to Chinese leaders about the visa delays when he visited Beijing in early December.

Americans, Chinese Sour on Each Other

With U.S.-China tensions rising on several fronts, American and Chinese public attitudes toward the other side worsened in 2013.

A survey by the Washington-based Pew Research Center showed that the percentage of American respondents with a favorable opinion of China dropped to 37 percent from 51 percent in 2011. A similar drop happened in China, with only 40 percent of Chinese respondents having a favorable view of the United States, down from 58 percent in 2010.

Fish said the increasingly unfavorable public attitudes also have influenced the way U.S. and Chinese leaders deal with each other.

"International relations are all about domestic politics - the U.S. policy toward China depends on how the officials behind that policy figure it is going to play to a U.S. audience," he said.

"That is even truer for China, whose government is far more sensitive to its own stability than the U.S. government. When Chinese leaders think about dealing with the United States, they think about how this is going to allow them to keep control of China," Fish explained.

Common Ground Remains

Despite the stresses in the U.S.-China relationship, the two nations’ longstanding economic ties and people-to-people exchanges were resilient.

For the United States, China kept its status as the second largest trading partner, third largest export market, and biggest source of imports.

Wertime of Tea Leaf Nation said he is a "stubborn optimist" about the relationship because of that common ground.

"Whether it is the $500 billion a year in trade, the $15 billion a year in direct investment, the millions of people who go back and forth to study, work or visit, these fundamental factors undergird our relationship and provide some counter-narrative to the fact that only a minority in each country express a favorable view of the other," he said.

The White House says the United States and China will expand their cooperation in 2014, focusing on addressing climate change, keeping energy markets well-supplied, and improving food and drug safety.